Prepare a medium hot fire in a charcoal grill with a cover, or preheat a gas grill to medium high. To make the patties, combine the toasted pine nuts,beef, red wine, 1 chopped tomato (1/4 " dice),1/2 cup crumbled feta cheese,1/4 cup chopped fresh mint leaves,salt, pepper, garlic and 4 tbsp of the Creamy Greek marinade:3/4 cup fat free yogurt, 2 tbsp balsamic vinegar and 2 tbsp X. V. olive oil.See recipe above.(Save the remainder for later use) Handle the meat as little as possible to avoid compacting the mixture. Mix thoroughly. Divide the mixture into 6 equal portions to fit into the 6-inch pita bread rounds. Brush the grill racks with olive oil. Place the patties on the racks , cover and grill until browned on the bottoms: 3-4 minutes. With a large spatula turn the patties carefully and continue to grill until done to an inside temperature of 160 degrees F for medium well. During the last few minutes add the pita bread rounds on the outer edges of the grill to toast lightly, keeping the bread warm until ready to serve. To assemble the burgers: Place lettuce leaves in bottom of pita breads,top with thick sliced tomatoes, the remaining 1/2 cup crumbled feta cheese, 1/2 cup chopped cucumbers,1/4 cup toasted pine nuts, 1/2 cup cooked sliced beets and pour the remaining Greek marinade over the vegetables.Top with grilled patty and slice pita rounds in half. Decorate with generous sprig of fresh mint.